/// <returns>Root of tree after turn</returns>
public static AvlTree <T> SmallRightTurn(AvlTree <T> root)
{
AvlTree <T> child = root.Left;
AvlTree <T> parent = root.Parent;
AvlTree <T> x = root.Right;
AvlTree <T> y = root.Left.Left;
AvlTree <T> z = root.Left.Right;
//Parents
child.Parent = parent;
root.Parent = child;
if (x != null)
{
x.Parent = root;
}
if (y != null)
{
y.Parent = child;
}
if (z != null)
{
z.Parent = root;
}
//Childs
root.Left = z;
root.Right = x;
child.Left = y;
child.Right = root;
if (parent != null)
{
if (parent.Right == root)
{
parent.Right = child;
}
else
{
parent.Left = child;
}
}
//Heights
long xH = x != null ? x.Height : -1;
long yH = y != null ? y.Height : -1;
long zH = z != null ? z.Height : -1;
if (zH > xH)
{
root.Height = zH + 1;
}
else
{
root.Height = xH + 1;
}
if (y.Height > root.Height)
{
child.Height = yH + 1;
}
else
{
child.Height = root.Height + 1;
}
UpdateHeight(child);
return(child);
}
/// <returns>Root of tree after turn</returns>
public static AvlTree <T> BigLeftTurn(AvlTree <T> root)
{
AvlTree <T> w = root.Left;
AvlTree <T> parent = root.Parent;
AvlTree <T> b = root.Right;
AvlTree <T> c = root.Right.Left;
AvlTree <T> z = b.Right;
AvlTree <T> x = c.Left;
AvlTree <T> y = c.Right;
//Parents
c.Parent = parent;
b.Parent = c;
root.Parent = c;
if (w != null)
{
w.Parent = root;
}
if (z != null)
{
z.Parent = b;
}
if (y != null)
{
y.Parent = b;
}
if (x != null)
{
x.Parent = root;
}
//Childs
if (parent != null)
{
if (parent.Right == root)
{
parent.Right = c;
}
else
{
parent.Left = c;
}
}
c.Left = root;
c.Right = b;
b.Left = y;
b.Right = z;
root.Left = w;
root.Right = x;
//Heights
long xH = x != null ? x.Height : -1;
long yH = y != null ? y.Height : -1;
long zH = z != null ? z.Height : -1;
long wH = w != null ? w.Height : -1;
if (wH > xH)
{
root.Height = wH + 1;
}
else
{
root.Height = xH + 1;
}
if (yH > zH)
{
b.Height = yH + 1;
}
else
{
b.Height = zH + 1;
}
if (b.Height > root.Height)
{
c.Height = b.Height + 1;
}
else
{
c.Height = root.Height + 1;
}
UpdateHeight(c);
return(c);
}
/// <returns>Root of tree after remove</returns>
public static AvlTree <T> Remove(AvlTree <T> item)
{
AvlTree <T> parent = item.Parent;
//Leaf
if (item.Left == null && item.Right == null)
{
if (parent == null)
{
return(null);
}
if (parent.Left == item)
{
parent.Left = null;
}
else
{
parent.Right = null;
}
UpdateHeight(parent);
return(Balance(parent));
}
//One child
if ((item.Left == null) ^ (item.Right == null))
{
if (item.Left != null)
{
if (parent != null)
{
if (parent.Left == item)
{
parent.Left = item.Left;
}
else
{
parent.Right = item.Left;
}
UpdateHeight(parent);
}
item.Left.Parent = parent;
return(Balance(item.Left));
}
else
{
if (parent != null)
{
if (parent.Left == item)
{
parent.Left = item.Right;
}
else
{
parent.Right = item.Right;
}
UpdateHeight(parent);
}
item.Right.Parent = parent;
return(Balance(item.Right));
}
}
//Two child
if ((item.Left != null) && (item.Right != null))
{
AvlTree <T> prev = Previous(item);
Remove(prev);
item.Key = prev.Key;
}
return(Balance(item));
}